In a construction vehicle, there has been widely used a heavy load tire for a construction vehicle in which a rotating direction is not specified (a non-directional property is provided) (for example, refer to patent document 1).
A non-directional lug pattern is formed on a tread surface of the heavy load tire for the construction vehicle mentioned above. For example, as shown in FIG. 6, lug grooves 80 are formed on a tread surface portion 87 of a tread portion 86 of the heavy load tire for the construction vehicle according to a related art 1, at a predetermined interval in the same direction as a tire width direction.
In recent years, in the heavy load tire for the construction vehicle mentioned above, it becomes a mainstream to attach a predetermined angle to a lug groove of the lug pattern, for securing an edge component in a width direction, securing a heat radiation performance, and solving a vibration problem. For example, as shown in FIG. 7, in a pneumatic tire according to a related art 2, lug grooves 90 of a tread surface portion 97 are formed so as to be in parallel to each other at an angle θ with respect to a tire width direction.
However, in the case that the lug groove 90 inclined with respect to a tire width direction U, such as the heavy load tire for the construction vehicle according to the related art 2, there is a problem that the lug groove 90 wears at an early stage only in a land portion 93 at one side of the lug groove 90 near a quarter point Q at which a distance from a tread end T is one half of a length from the tread end T to a tire equatorial plane, and a one-side biased abrasion is generated (refer to FIGS. 8 and 9).
In this case, since an input of a side force is large in the case that the heavy load tire for the construction vehicle is installed to a front side, this matter particularly remarkably appears.
Further, as a technique of suppressing the biased abrasion of the tread so as to improve a tire life (an abrasion resistance), there is a technique, for example, disclosed in patent document 2. This is structured such as to increase a rigidity at a shoulder side and suppress a biased abrasion at a shoulder side by arranging a lot of volume of a tread rubber close to the shoulder rather than the tread pattern of the conventional tire. However, according to this related art, a certain degree of improvement of the abrasion resistance appears, however, there is a demand of further improving the abrasion resistance near an intermediate portion between the tire equatorial plane and a ground contact end of the tread, so-called one quarter point, in a market.    Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 2000-233610    Patent Document 2: Japanese Patent Application Laid-Open (JP-A) No. 2001-225608